Python 3 Completion in Vim

First off, the Vim that ships with Ubuntu 14.04 doesn’t support Python 3. Run:

vim --version | grep python

and you get:

-python3

Two ways around it: compile it yourself with the right flags, or just use a ready-made PPA:

sudo apt-add-repository ppa:pi-rho/dev
sudo apt-get update
sudo apt-get install vim

After installing, don’t forget to run that command again and check whether python3 has turned into a plus sign.

The latest jedi supports Python 3, so completion built on jedi is viable.

First install jedi. See the official instructions for how; whether you use virtualenv is up to you. I just installed it system-wide.

sudo pip3 install jedi

Next, install the jedi-vim and neocomplete plugins for your vim. In your vim config, neocomplete is the main act, with jedi-vim alongside it:

You can copy neocomplete’s Configuration Examples as-is. A few things to watch out for:

Replace:

autocmd FileType python setlocal omnifunc=pythoncomplete#Complete

with:

autocmd FileType python setlocal omnifunc=jedi#completions

Then add the following lines, if you don’t already have them:

let g:neocomplete#enable_auto_select = 0
let g:jedi#popup_select_first=0
set completeopt=longest,menuone
let g:jedi#auto_vim_configuration = 0
let g:jedi#popup_on_dot = 0
if !exists('g:neocomplete#force_omni_input_patterns')
        let g:neocomplete#force_omni_input_patterns = {}
endif
let g:neocomplete#force_omni_input_patterns.python = '\%([^. \t]\.\|^\s*@\)\w*'

The most important bit: jedi-vim conflicts with the Python-mode plugin bundle. Disable the latter, and pull out whichever pieces you actually need and install them separately.

If you get an error on startup:

that means Vim is having trouble calling into lua support. Inside Vim, run:

:lua print('KThentai')

and you get:

Some searching told me it’s the missing libluajit-5.1.so.2 file. No idea when it went missing. Just put it back:

sudo apt-get install libluajit-5.1-2

And then Python 3 completion works fine in vim. So far everything’s normal except for a few statements under PyQt5 that don’t complete.